Morgan Stanley, the lead investment bank in Facebook's flotation, will
compensate investors who overpaid, according to a person familiar with the
matter.

The source said the firm was reviewing Facebook orders made by its retail clients and would make adjustments if they paid too much. But there was no confirmation as to exactly what amount would constitute an overpayment.

Facebook's IPO was highly anticipated but technical problems on the Nasdaq delayed the opening last Friday. The stock closed nearly flat on its first trading day at $38.23 (£24.50).

Morgan Stanley and Facebook face at least two lawsuits over the IPO. Both actions claim analysts at the large underwriting investment banks cut their second-quarter and full-year forecasts for Facebook just before the flotation and told only a handful of clients.

It is claimed that several major investors had been pre-warned that a Morgan Stanley analyst had cut the amount of money he expected Facebook to make. The advance notice allowed the investors to either avoid the stock completely or sell immediately after they floated at $38.

"The allegations, if true, are a matter of regulatory concern," said Rick Ketchum, the head of the Financial Industry Regulatory Authority earlier this week.

Mary Schapiro, head of the Securities and Exchange Commission, said on Wednesday: “There is a lot of reason to have confidence in our markets and the integrity of how they operate, but there are issues we need to look at specifically with regard to Facebook.”

Morgan Stanley has declined to comment on the lawsuits and Facebook described them as "without merit".

Yesterday Facebook's stock closed up $1.03, or 3.2pc, at $33.03. This gives the company a market value of $90.4bn, down from $105bn at the end of trading last Friday.